Past research

Numerous rivers and lakes.

Cycling of dissolved organic matter (DOM) in permafrost and glacier melt water impacted freshwater systems of the Canadian Arctic

My research focuses on the distribution and dynamics of dissolved organic matter (DOM) in freshwater systems of the Canadian Arctic. Permafrost and glacier melt water fluxes represent potential vectors for changes in carbon cycling that may render more significant impacts based on a changing climate. The chemical composition of DOM is often instrumental in dictating several key biogeochemical roles that it plays in natural waters. As such, I’m interested in approaching a better understanding of sources and sinks of DOM by applying various techniques to advance its characterization. 

- Paul Dainard, PhD (2021)

Past projects

Research projects conducted by the environmental geochemistry lab focus on the cycling of key elements within lakes, streams, rivers, forests, and agricultural watersheds. Understanding these cycles is critical to properly addressing environmental concerns. Ultimately, the lab's research aims to inform decision-makers about current and emerging environmental problems and the nature of potential solutions. As a result, the lab draws its influences from a wide range of disciplines from isotope geochemistry to ecosystem ecology.

Currently, our research focuses on the effects of agricultural and other anthropogenic inputs on the combined biogeochemical cycles of oxygen, nitrogen, and phosphorus in eutrophic ecosystems; and carbon dioxide and methane cycling in both natural and modified boreal lakes and wetlands. Our projects are multi-disciplinary and often bring together several research groups in order to make them as effective as possible. We typically employ natural abundance isotopes and other tracers to examine the biogeochemical processes that drive ecosystem function.

Groundwater nitrate contamination in agricultural regions

Nitrate is the most ubiquitous groundwater contaminant in southern Ontario. Wetlands and narrow riparian zones can attenuate agricultural nitrate if the hydrogeology and geochemistry is suitable. Mechanisms controlling nitrate attenuation are currently being examined in riparian zones ranging from narrow grassed buffer strips to wetlands in a variety of hydrogeologic settings. Several field sites within close proximity to Waterloo have been established. Researchers in this field program include Dr. M. English and Dr. R. Petrone at Wilfrid Laurier University, Dr. R. Aravena, Dr. D. Rudolph and Dr. W. Robertson of Waterloo, and Dr. J. Spoelstra at Environment Canada.

Septic system impacts

Phosphorus (P) from septic systems is of concern for surface water quality and limits the number of cottages on many lakes. Septic system P is partially attenuated under septic tilefields but the mechanisms controlling the attenuation, the stability of the attenuating phases and thus the amount of natural attenuation are poorly known. Recent investigations, including both field and laboratory studies, at a number of extensively instrumented sites have focused on the role of Anammox in nitrogen attenuation, the lability of DOC in groundwater, and the role of ritrous oxide as an early indicator of denitrification. Septic system research is conducted with Dr. Will Robertson, Ramon Aravena, Dr. Josh Neufeld of the University of Waterloo, and Dr. John Spoelstra of Environment Canada.

Origin and cycling of DOC in forested catchments; Clues from radioactive (14C) and stable (13C, 15N) isotopes

Dissolved organic carbon (DOC) can be an important component of the acid-base balance and the food web, has a major role in the mobility and toxicity of trace metals and other contaminants, affects light penetration and offers protection to aquatic organisms from the effects of UV radiation. Work on DOC is part of research program designed to examine carbon cycling and the turnover times of various carbon reservoirs in forested watersheds on the Canadian Shield. Our approach involves the use of 13C, 15N and 14C to examine the sources and transformations of DOC. Other researchers involved in this project are Dr. Ramon Aravena and Dr. Barry Warner of Waterloo. Field work is conducted at a number of sites including Harp and Plastic Lakes, Turkey Lake Watershed, the Experimental Lakes Area and agricultural basins in Southern Ontario.

Nitrogen and sulfur cycling in a sugar maple forest: insights from stable isotopic ratios

Turkey Lakes Watershed (TLW), located near Sault Ste Marie Ontario is an intensive ecological monitoring site maintained by The National Water Research Institute (NWRI) of Environment Canada. One of the goals for this site is the assessment of ecosystem impacts of the atmospheric deposition of sulfur and nitrogen compounds. Our collaboration involves the application of new isotopic techniques to the understanding of nitrogen cycling at the TLW. This overmature forest has a moderate atmospheric N deposition load but exports significant amounts of NO3. During the second phase of this work, a forestry experiment was initiated, involving a removal of all trees larger than a diameter of 10 cm from the principal basin of our research.

Two adjacent forested catchments: Dramatically different NO3export

Two adjacent terrestrial catchments at Harp Lake have similar soils, overburden depth, vegetation cover, and measured soil N-mineralization and nitrification rates. Both catchments receive high rates of nitrogen deposition typical for central Canada. Despite these similarities, annual stream nitrate export from one catchment is a factor of 10 larger than the other catchment. In the catchment that exports nitrate, streamwaters and groundwaters have fall, winter and spring nitrate concentrations in excess of average throughfall values. Both 18O/16O and 15N/14N isotopic signatures of the nitrate in precipitation, snowpack, and soil ground and stream waters as well as 15N/14N in leaves, soils and dissolved organic nitrogen were analyzed to examine the contributing nitrate sources.

Flooding of boreal forest uplands and wetlands for reservoir creation

Hydroelectric power generation has become an attractive alternative to thermal power generation because it has been widely accepted as a carbon-free source of energy. Approximately two-thirds of Canada’s installed electrical energy generating capacity is hydroelectric based, with plans for expansion of current reservoir systems flooding boreal landscapes. Boreal forests act as a small CO2 sink with respect to the atmosphere due to long-term carbon accumulation in soils, and dry upland boreal soils are an important sink for atmospheric CH4 via microbial oxidation. While all boreal reservoirs studied to date emit both CO2 and CH4 to the atmosphere, the degree to which reservoirs influence atmospheric CO2 and CH4 levels is uncertain. Extensive pre-flood landscape CO2 and CH4 flux data from past studies is lacking, so our understanding of the net effect of reservoir creation on boreal landscapes is incomplete. Furthermore, GHG flux data alone provides no information on within-reservoir carbon cycling processes controlling GHG emissions.

Two experimental reservoir projects (ELARP and FLUDEX) were conducted at the IISD Experimental Lakes Area (IISD-ELA) to study the net change in greenhouse gas (GHG) flux to the atmosphere and to better understand the processes causing elevated methylmercury levels in biota after flooding.

The ELA (50 km east-southeast of Kenora, Ontario) was established as a place where it is possible to perform whole ecosystem experiments, initially to study eutrophication in the St. Lawrence-Great Lakes system, particularly Lake Erie. Historically research has focused on eutrophication, acidification, trace metal dynamics and limnological processes. More recently, the focus has switched to reservoir effects (GHGs and mercury), hormonal mimicry, climate change effects, and mercury and nanoparticle dynamics.

The Experimental Lakes Area Reservoir project (ELARP) was a 16.7 ha wetland complex flooded annually between 1993 and 2000(Kelly et al. 1997). Large increases in greenhouse gas emissions and Hg concentrations in fish were observed. In 1999, 3 upland enclosures were flooded (FLUDEX) to contrast the results of flooding of 3 different types of vegetation and soil moisture regimes and to compare these upland results to the results obtained by flooding of the ELARP wetland. This research was conducted with Dr. Ramon Aravena of Waterloo and in cooperation with scientists from Fisheries and Oceans, Canada, University of Alberta, University of Manitoba, University of Wisconsin and the United States Geological Survey

Our role in these studies has involved examining the isotopic composition (13C and 14C) of CO2, CH4 and DOC to discern the sources and processes affecting greenhouse gas production and carbon decomposition. By using13C:12C of DIC, CH4 and DOM we determine the importance of GHG producing processes (carbon mineralization/respiration, methanogenesis, methane oxidation). By using 13C:12C of DIC and 18O:16O of O2 we determine the rate of gross primary production and its role in GHG cycling and O2 regime of the reservoirs. Subsequently, a process-based model of the reservoirs will be constructed and used to predict the potential GHG flux from existing and planned reservoirs.